Abstract

Irregular masses and flat slabs of vesicular, slaglike, and glassy melt (referred to herein as Edeowie glass) are locally abundant on a desert plain in central South Australia, where the material appears to be associated with an old land surface being exhumed by deflation and water erosion. The slabs of melt are associated with outcrops of baked sediment having very similar geochemistry, suggesting an origin by in situ surface fusion. Embedded clasts displaying shock metamorphism in quartz suggest that the thermal source may have been in some way associated with an impact event, although an obvious crater is lacking. If Edeowie glass is related to impact, a different thermal mechanism from that generally ascribed to the production of impact melt is required because of evidence for in situ generation of melt distal from any crater. 40Ar/39Ar laser probe dating of two samples has produced overlapping dates of 0.67 ± 0.07 and 0.78 ± 0.33 Ma.